Functional-group-directed diastereoselective hydrogenation of aromatic compounds. 1

Diastereoselective liquid phase hydrogenation of a series of monosubstitute d indane and tetralin substrates was studied on supported rhodium catalysts . Predominantly the cis-cis diastereomer, obtained by hydrogenation from th e diastereoface opposite the substituent (at the stereogenic center), and t he cis-trans diastereomer, obtained by hydrogenation from the diastereoface on the same side as the substituent, were formed. The diastereoselectivity between the two isomers was dependent on the steric repulsion or the elect ronic attraction of the substituent with the surface of the catalyst. The h ydroxyl group did not exhibit a strong attraction (haptophilicity), and the cis-cis diastereomer was obtained as the major product. The amino group ex hibited a very high haptophilicity, yielding primarily the cis-trans diaste reomer. The diastereoselectivity obtained in the hydrogenation of all the s ubstrates was influenced on addition of bases to the reaction mixture. In t he case of alcoholic substrates, the selectivity to the cis-trans diastereo mer could be substantially increased with alkaline hydroxide additives.